Photography using silver halide is superior in photographic characteristics such as sensitivity and control of gradation to other photographic processes such as electro-photography and diazo photography and thus has been widely used. Another technique has recently been developed in which the image forming processing of light-sensitive materials using silver halide is carried out by a dry process such as by heating in place of the conventional wet process using developers, for example, so that the desired image can be obtained in a simplified manner and rapidly. In this technique, heat developable light-sensitive materials using silver halide are used.
These heat developable light-sensitive materials are known and details thereon are given in, for example, Shashin Kogaku no Kiso, Corona Co., pages 553-555 (1979), Eizo Johoh, page 40, April (1978), and Nebletts Handbook of Photography and Reprography, 7th ed., Van Nostrand Reinhold Co., pages 32-33.
In conventional procedures, however, reduced silver images and color images are simultaneously formed in exposed areas after heat development and, therefore, the color images are turbid, cannot be stored for long periods of time, and are gradually colored during storage. That is, the conventional procedures fail to provide images which are sharp and satisfactory for practical use.
In order to overcome the above problems, a light-sensitive material and a method of forming images using the light-sensitive material have been proposed in Japanese Patent Application (OPI) Nos. 149046/83 and 168439/84 (the term "OPI" as used herein means a "published unexamined Japanese patent application"). In these methods, mobile dyes formed imagewise are transferred to a dye fixing layer. For this dye transfer, solvents such as water, basic aqueous solutions, alcohols, and dimethylacetamide are supplied, or, alternatively, hydrohilic thermal solvents are previously incorporated in the materials, whereby independent application of a solvent(s) from the outside can be omitted. In respect of convenience, the latter is advantageous over the former.
In the above image forming method, dye-releasing activator such as bases, for example, are conveniently used so that color images of high density can be rapidly formed.
One embodiment of an image forming method is such that a dry fixing material comprising a support having provided thereon a dye fixing layer is separately prepared from a light-sensitive material and a dye image is fixed in the dye fixing material. In this case, it is necessary for the dye fixing material and the light-sensitive material to be brought into close contact to such an extent that the transfer of the mobile dye can be sufficiently achieved and, furthermore, it is required that, after the transfer of the dye image is completed, the dye fixing material and the light-sensitive material can be readily separated apart without causing any damage to the two materials. In conventional heat developable light-sensitive materials, however, difficulties are sometimes encountered in the above separation process and thus they have been desired to be improved in this respect. Particularly, in the case that there is employed a dry dye fixing step where a light-sensitive material and a dye fixing material are superposed and heated in a substantially water-free condition, the above problem is liable to occur and a good dye image cannot be obtained because an emulsion of the light-sensitive material sticks to the dye fixing material.